transmission between neurons Flashcards
(18 cards)
What is synaptic transmission?
The process by which neurons communicate using chemical messengers (neurotransmitters) across a synapse.
What is a synapse?
The junction between two neurons, consisting of the terminal button of one neuron and the membrane of another.
What triggers an action potential?
Local depolarisation reaching a threshold (~ -55mV), causing voltage-gated Na⁺ channels to open.
Why is an action potential described as “all-or-nothing”?
Because once the threshold is reached, a full action potential always occurs—no partial signals are sent.
What is the role of potassium (K⁺) channels during an action potential?
They open after Na⁺ channels, allowing K⁺ to exit the cell, repolarising and briefly hyperpolarising the membrane.
How do myelinated and unmyelinated axons differ in signal transmission?
Myelinated axons use saltatory conduction (faster); unmyelinated axons use continuous conduction (slower).
What is saltatory conduction?
A faster, more efficient method where the action potential “jumps” between nodes of Ranvier on a myelinated axon.
What are ionotropic receptors?
Receptors that directly open ion channels when a neurotransmitter binds. Fast-acting.
What are metabotropic receptors?
Receptors that initiate a slower, energy-requiring chain reaction to open ion channels.
What is an EPSP?
An excitatory postsynaptic potential that increases the likelihood of the neuron firing.
What is an IPSP?
An inhibitory postsynaptic potential that decreases the likelihood of the neuron firing.
What is neural integration?
The summation of EPSPs and IPSPs to determine if a neuron will fire.
How are neurotransmitters removed from the synapse?
Through enzymatic deactivation (e.g., acetylcholinesterase) or reuptake into the presynaptic neuron.
What is an agonist drug?
A drug that mimics a neurotransmitter and enhances synapse function.
What is an antagonist drug?
A drug that blocks the effect of a neurotransmitter.
Which ion enters the terminal button during an action potential?
Ca²⁺ (Calcium)
Where are neurotransmitters stored before release?
In vesicles in the presynaptic terminal.
After crossing the synapse, where do neurotransmitters bind?
To receptors on the postsynaptic membrane.
